Im not very technically skilled so I dont know which menu you mean and where to update the metadata.
I looked at what u linked but I dont understand most of it…
run the command i gave you to install it, then type gnome-firmware in terminal to start the program, then update metadata from the menu, then just select the uefi and click upgrade.
you can install it in other ways. Like using their boot medium, or windows
even linux has other ways to flash firmwares low-level if you have the firmware file from lenovo. But i highly recommend you don’t look into this method as just one wrong command can leave your motherboard bricked.
gnome.firmware did not show that kind of version number, so either you need to look for it at during when you boot the computer, or when you enter UEFI settings at boot.
Alternatively just make a bootable media using that file, and try it. If you have latest it does nothing. If you don’t it will update.
Due to grub and luks2 decryption - boot is taking a long time when you are using full disk encryption.
There is nothing that is going to change that.
It is possible to migrate your system to use systemd boot instead - this will cut down on your loading time - but it requires a little work - and there is tradeoffs.